Targeted temperature management (TTM), occasionally still referred to as therapeutic hypothermia and de- fined as whole body cooling to between 32 and 36 C for 12-24 hours, is currently recommended for comatose adults recovering from out-of-hospital cardiac arrest (OHCA) resuscitation, in an attempt to attenuate reperfu- sion injury, preserve neurological function, and improve survival. Though TTM has been clearly shown to bene- fit patients less than 75 years of age, it has never been specifically evaluated in older adults - the fastest grow- ing demographic in developed countries. Since those 75 years of age and older have a relatively shorter base- line life expectancy, and often have multiple co-morbidities that put them at greater risk for complications of treatment, they must be considered a distinctly different subset of adult OHCA survivors. There is tremendous uncertainty regarding TTM in this age group, so we propose to address this as an important knowledge gap. We will analyze outcomes for age subgroups among the elderly using the well-characterized Cardiac Arrest Registry to Enhance Survival (CARES) dataset. The objective of this proposal, using a retrospective study de- sign, is to assess the effectiveness of TTM on survival and neuroprotection in geriatric OHCA survivors. The rationale for this study is that TTM has been extrapolated beyond its proven indication to include this vulnera- ble population with no convincing evidence and unknown consequences, so we seek to determine its effec- tiveness in this cohort. Our central hypothesis is that elderly patients provided TTM will have lower in-hospital mortality and more favorable neurological status at hospital discharge than those not treated. Using the CARES data, we will compare the proportion of OHCA survivors =75 years of age, alive at hospital discharge across predefined age categories. We will also compare the proportion of good neurological status (Cerebral Performance Category [CPC] at hospital discharge in OHCA survivors =75 years of age across predefined age categories. This research is significant because it will generate a large, robust, multi-center, comparative effec- tiveness analysis of TTM in geriatric OHCA survivors. It is innovative in that we will be accessing a unique, un- tapped repository of prospectively collected and validated data to determine the effectiveness of TTM in the elderly, which has never before been done. Our results will provide preliminary data for a prospective cohort study that will externally corroborae our findings and provide a higher level of scientific evidence regarding the appropriate application of TTM in the elderly. This line of investigation will lead to important clinical practce changes (i.e., age specific modification of existing TTM guidelines), and secure the highest quality of care for individuals in this rapidly growing segment of society, so that they can live longer and more fulfilling lives.